Mike Deposit

Site Name

Primary: Mike Deposit
Secondary: Main Mike
Secondary: West Mike
Secondary: part of Newmont?s Carlin-South operations

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Commodity

Primary: Silver
Primary: Gold
Secondary: Lead
Secondary: Zinc
Secondary: Copper
Tertiary: Iron
Tertiary: Antimony
Tertiary: Bismuth
Tertiary: Tungsten
Tertiary: Arsenic
Tertiary: Molybdenum

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Location

State: Nevada
County: Eureka
District: Carlin Trend

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Land Status

Land ownership: BLM Administrative Area
Note: the land ownership field only identifies whether the area the mine is in is generally on public lands like Forest Service or BLM land, or if it is in an area that is generally private property. It does not definitively identify property status, nor does it indicate claim status or whether an area is open to prospecting. Always respect private property.
Administrative Organization: Elko BLM Administrative District

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Holdings

Not available

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Workings

Not available

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Ownership

Owner Name: Newmont Gold Corp.
Info Year: 2004

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Producer
Deposit Type: disseminated; Pluton-related poly metallic skarn
Operation Type: Surface
Discovery Year: 1989
Years of Production:
Organization:
Significant: Y
Deposit Size: M

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Physiography

Not available

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Mineral Deposit Model

Model Name: Sediment-hosted Au
Model Name: Skarn Cu

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Orebody

Form: tabular

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Structure

Type: R
Description: Deposits in the Maggie Creek subdistrict are primarily hosted by lower-plate carbonate and clastic rocks of Devonian and Silurian age exposed in a domed window through the Roberts Mountains allochthon. The Carlin window is an erosionally breached, northwest-trending anticlinorium, exposing an autochthonous core beneath upperplate, siliceous and carbonate-clastic rocks of Devonian to Ordovician age in the Roberts Mountains overthrust sheet. Lower-plate exposures are bound by high-angle, normal faults on the southeastern, southwestern, and northwestern flanks of the Schroeder Mountain uplift. The margins of the window are down-faulted, and disconformably overlain by volcaniclastic sedimentary rock and gravel of the Tertiary Carlin Formation. Most of the deposits are in the southwestern part of the Carlin Window in a mile-wide northwest-elongated belt of subdued topography along and in the footwall of the Good Hope reverse fault between Marys and Schroeder Mountains called the Tusc Corridor.

Type: L
Description: Carlin-type gold mineralization is concentrated along the northwest-dipping Soap Creek fault, the northwest-striking, northeast-dipping Good Hope reverse fault, and the west-dipping Valley fault.

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Alterations

Alteration Type: L
Alteration Text: Alteration products include sooty pyrite/marcasite, variable silicification, kaolinite, sulfide-silica-matrix breccia, dissolution-collapse breccia, and quartz-orpiment veins.

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Rocks

Role: Associated
Age Type: Associated Rock Unit
Age in Years: 38.000000+-
Age Young: Middle Eocene

Role: Associated
Age Type: Associated Rock Unit
Age in Years: 37.000000+-
Age Young: Late Eocene

Role: Associated
Age Type: Associated Rock Unit
Age Young: Oligocene

Name: Intermediate Volcanic Rock
Role: Host
Description: mafic to intermediate dikes
Age Type: Host Rock
Age in Years: 107.000000+-
Age Young: Early Cretaceous

Name: Mafic Intrusive Rock
Role: Host
Description: mafic to intermediate dikes
Age Type: Host Rock
Age in Years: 107.000000+-
Age Young: Early Cretaceous

Name: Siltstone
Role: Host
Description: calcareous
Age Type: Host Rock
Age Young: Middle Devonian
Age Old: Late Devonian

Name: Hornfels
Role: Host
Description: light- to dark-gray calcsilicate
Age Type: Host Rock
Age Young: Middle Devonian
Age Old: Late Devonian

Name: Siltstone
Role: Host
Age Type: Host Rock
Age Young: Early Devonian
Age Old: Wenlock

Name: Argillite
Role: Host
Description: siliceous
Age Type: Host Rock
Age Young: Early Devonian
Age Old: Wenlock

Name: Chert
Role: Host
Description: argillaceous
Age Type: Host Rock
Age Young: Early Devonian
Age Old: Wenlock

Name: Siltstone
Role: Host
Description: calcareous
Age Type: Host Rock
Age Young: Early Devonian
Age Old: Wenlock

Name: Limestone
Role: Host
Description: sandy
Age Type: Host Rock
Age Young: Early Devonian
Age Old: Wenlock

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Analytical Data

Not available

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Materials

Ore: Powellite
Ore: Sphalerite
Ore: Galena
Ore: Chalcopyrite
Ore: Pyrite
Ore: Sphalerite
Ore: Galena
Ore: Chalcopyrite
Ore: Molybdenite
Ore: Quartz
Ore: Diopside
Ore: Garnet
Ore: Stibnite
Ore: Scheelite
Ore: Gold
Gangue: Pyrite

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Comments

Comment (Workings): drilling

Comment (Location): The Mike Deposit is located about three miles northwest of the Gold Quarry Mine, and about a mile northwest of the Tusc deposit, on the eastern flank of the Tuscarora Mountains.

Comment (Deposit): Mike is at the northwest end of a 3-mile (5-km) long belt of Carlin-type gold deposits aligned along the footwall of the northwest-striking, northeast-dipping Good Hope fault. Mike is subdivided into the West Mike deposit in the footwall of this apparent reverse fault and the Main Mike deposit along the fault and in the hanging wall. Contact-metamorphic, Carlin-type, and secondarily enriched mineral systems are hosted in variable hornfels after Silurian to Devonian carbonate and siliciclastic rocks of the Roberts Mountains Formation, Popovich Formation, and Rodeo Creek unit, and in mafic to intermediate dikes of at least 107 Ma age. Contact-metamorphic mineralization is coincident with potassium metasomatism dated at 111-107 Ma, and the formation of hornfels and local skarn. Mineralization typically consists of quartz-sulfide veins dominated by coarse-grained pyrite and iron-rich sphalerite with minor galena, chalcopyrite, and molybdenite. Quartz-carbonate veins hosting an arsenic-bismuth-lead-silver sulfosalt also occur throughout the deposit. At northwest West Mike, sphalerite-dominated, replacement-style base-metal mineralization is concentrated along the contact between the Rodeo Creek unit and the Popovich Formation. West Mike gold mineralization is roughly flat-lying and stratiform, and segregated into upper and lower zones. The upper zone is 200 to 450 feet (60-135 m) thick, decarbonatized, oxidized, and grades 0.025 opt (0.86 g/t) gold. The lower zone has similar thickness, is partially oxidized, grades 0.080 opt (2.7 g/t), and is coincident with a 70- to 200-foot (21-60 m) thick dolomitic front at the base of decarbonatization. Gold at Main Mike grades an average 0.037 opt (1.2 g/t) and occurs in an oxidized and decarbonatized zone at the intersection of the Soap Creek and Good Hope faults. Sulfide-zone gold at the Mike deposit occurs in micron-size, arsenian pyrite rims coating euhedral, coarser-grained pyrite. Oxide-zone copper occurs in copper silicates, clays, arsenates, phosphates, oxides, and carbonates. Copper is sited in chalcocite and locally covellite in the top-of-sulfide zone and in sulfide lenses in overlying oxidized rock. Copper-bearing zones are typically decarbonatized, clay altered, alunite veined/replaced, and iron oxide stained. Oxide gold deposits at both Main Mike and the analogous Tusc, 4,000 feet (1,200 m) to the southeast, contain higher-grade (>0.05 opt [1.7 g/t]), flat-lying, bedding-discordant cores-possible supergene upgrades. Mineralization is completely covered by postmineral volcaniclastic sediment of the Tertiary Carlin Formation.

Comment (Development): The earliest prospecting in the Maggie Creek district was in the 1870s, and several hundred tons of gold, silver, copper, and lead ores were produced through 1952. In the 1880s, oxide-copper mineralization was discovered on the Copper King claims, one mile (1.6 km) southeast of the Mike deposit area and directly southwest of the Tusc gold mine area. The Copper King Mine produced approximately 14,800 short tons of oxide ore that averaged 3.4 wt.% copper from underground workings and small open cuts from 1952 through 1958. Occidental Minerals Corporation explored for a northwest extension of this ore during the early 1970s and drilled three holes through the later-defined Good Hope copper lobe of the Mike deposit. Occidental identified a blanket of secondary copper oxides and chalcocite in the Paleozoic section plunging beneath increasingly thicker Tertiary cover towards the northwest, but did not define economic copper mineralization. After a series of economic discoveries at Gold Quarry, Mac, and Tusc during the late 1970s and the 1980s, Newmont Mining Corporation discovered the Main Mike gold deposit in 1989, using an exploration strategy of tracking gold mineralization along the northwest extension of the Good Hope fault from Gold Quarry and Tusc under postmineral cover to the postulated intersection with the Soap Creek fault. Definition of the deposit through infill drilling and further exploration resulted in the discovery of the West Mike gold deposit and the Corridor copper lobe in 1992, and expansion of the gold and copper resources at both West and Main Mike in 1993 and 1994. Widespread occurrence of oxide copper minerals in core prompted estimates of copper inventories for Main Mike and West Mike. Renewed exploration in 1997-2000 resulted in delineation of the West Mike lower gold zone, expansion of the West Mike copper resource, and discovery of a deposit-wide blanket of zinc.

Comment (Commodity): Ore Materials: gold, arsenian pyrite, iron-rich sphalerite, galena, chalcopyrite

Comment (Commodity): Gangue Materials: pyrite, iron-rich sphalerite, galena, chalcopyrite, molybdenite, quartz, carbonate, arsenic-bismuth-lead-silver sulfosalt, diopside, garnet, stibnite, scheelite, powellite

Comment (Economic Factors): The total 1999 drill-indicated mineral inventory for the Main Mike and West Mike deposits is: 408 million short tons (370 million tonnes) of gold ore grading 0.021 ounces of gold per ton (0.72 g/t) for a total 8,568,000 contained ounces of gold (266 tonnes); 151 million short tons of ore containing 0.34 wt.% copper for a total of 1,027 million pounds of copper; and 19 million short tons of ore containing 2.13 wt.% zinc for a total of 809 million pounds of zinc.

Comment (Geology): A copper-molybdenum-gold porphyry northwest of Mike is inferred by the distributions of hornfels, potassium feldspar, tungsten, and molybdenum. This porphyry and associated mesothermal mineral system are inferred to be Cretaceous based on the age of apparently related replacement-style potassium feldspar at Mike. Sphalerite-dominated quartz veins at Mike also suggest a location peripheral to a zoned porphyry system. Secondary copper, zinc, and silver concentrations diminish to the southeast, indicating a source of these metals to the northwest.

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References

Reference (Deposit): Mcfarlane, D., 1992, Gold Production on the Carlin Trend, in Buffa, R. and Coyner, A., eds., Geology and Ore Deposits of the Great Basin-Field Trip Guidebook Compendium, The Geological Society of Nevada, Reno, p. 841-843.

Reference (Deposit): NBMG, 1994, MI-1993

Reference (Deposit): Arkell, B., 1992, Geology of the Tusc and Mac Deposits, in Buffa, R. and Coyner, A., eds., Geology and Ore Deposits of the Great Basin-Field Trip Guidebook Compendium, The Geological Society of Nevada, Reno, p. 862-864.

Reference (Deposit): Schull, H.W., 1991, The Lithostratigraphy and Sedimentology of the Contact/Transition Between the Roberts Mountains Formation and the Western Facies Rocks in the Carlin Mining District, Eureka and Elko Counties, Nevada, in Raines, G.L., et al., eds., The Geology and Ore Deposits of the Great Basin, The Geological Society of Nevada, Reno, p. 705-712.

Reference (Deposit): Rota, J., 1990, Geology and Mineral Deposits of the Maggie Creek Subdistrict, Carlin Trend, Eureka County, Nevada, Oral Presentation at Great Basin Symposium, The Geological Society of Nevada, Sparks, NV, April, 1990.

Reference (Deposit): Ekburg, C., Rota, J., and Arkell, B., 1991, Geology and Mineral Deposits of the Maggie Creek Subdistrict, Carlin Trend, Eureka County, Nevada, in Raines, G.L., et al., eds., The Geology and Ore Deposits of the Great Basin, The Geological Society of Nevada, Reno, p. 625-633.

Reference (Deposit): John W. Norby and Michael J.T. Orobona, 2002, Geology and Mineral Systems of the Mike Deposit; in Gold Deposits of the Carlin Trend, NBMG Bull. 111.

Reference (Deposit): Long, K.R., DeYoung, J.H., Jr., and Ludington, S.D., 1998, Database of significant deposits of gold, silver, copper, lead, and zinc in the United States; Part A, Database description and analysis; part B, Digital database: U.S. Geological Survey Open-File Report 98-206, 33 p., one 3.5 inch diskette.

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Nevada Gold

Nevada has a total of 368 distinct gold districts. Of the of those, just 36 are major producers with production and/or reserves of over 1,000,000 ounces, 49 have production and/or reserves of over 100,000 ounces, with the rest having less than 100,000 ounces. Read more: Gold Districts of Nevada.